110
Marine Mammal Physiology: Requisites for Ocean Living
other ursids, reflecting the increased biomechanical pressures for consuming a primarily
marine mammal diet (Slater et al. 2010). Polar bears tend to grasp their prey with their
mouths and break the neck or skull of their prey with their large masticatory muscles
and robust dentition. Interestingly, their cranial morphology and feeding biomechanics
demonstrates a potential trade-off leaving polar bears less effective at processing tough
food matter associated with omnivory (e.g., plants) (Slater et al. 2010). An ecomorphological study of craniodental morphology of all bears in relation to diet demonstrates significant morphological separation among bears that exhibit omnivory, herbivory, carnivory,
and insectivory. Only polar and brown bears exhibit significant carnivory. Craniodental
adaptations include a reduction in molar size, flexible mandibles, and relatively small carnassial blades. Polar bear feeding adaptations have more in common with omnivorous
canids. The less than robust feeding apparatus that might be expected from polar bears
can be explained by the fact that polar bears target ringed and bearded seal pups and
seals that are under 2 years of age (King 1983). These seals are much smaller in body size
and are much more vulnerable than larger prey. The size discrepancy suggests that polar
bears can overpower their prey without the need for craniodental adaptations (Sacco and
Van Valkenburgh 2004) that are typical in carnivorous canids that hunt large prey (Van
Valkenburgh and Koepfli 1993). However, polar bears are capable of taking larger prey
such as walruses and beluga whales (King 1983; Sacco and Van Valkenburgh 2004).
5.3 Tools and methods for studying feeding
strategies in marine mammals
Marine mammals are notoriously difficult to study both in the wild and in c aptivity.
As a consequence, much work on feeding mechanisms has been morphological.
Morphology can be used to predict function, but with caution, and should be considered
functional hypotheses until function can be verified by other methods. Regardless, craniodental morphology can be very instructive for investigating feeding mechanisms. Indeed,
new methods such as computed tomography, 3D reconstruction, 3D printing, finite element
analyses, physical and computation biomechanical modeling, materials science, and geometric morphometric are providing new and exciting frontiers in morphological research.
Advances in camera, video, computing, and electrophysiology capabilities and the reduction in size and increased portability are now allowing pool-side performance experiments that could have only been conducted in the laboratory in the past. This translates
into additional focused and experimental captive studies, which quantitatively measures
kinematics, performance, physiology, and behavior. Such experiments interface well with
field studies in which a cadre of animal-borne tags on free-ranging animals collects data
from foraging bouts and events in the open ocean. Such tools include integrated systems
that incorporate time–depth recorders with video systems, oceanographic data collection
systems, and 3D movement sensors (accelerometers, magnetometers, and gyroscopes) that
can record behavior, body movement, visual perspective, acoustics, and physiology. New
unmanned aerial vehicles (UAVs) are providing new access and perspective to animal
behavior and beyond. It is an exciting time to be a marine mammalogist.
5.4 Future directions
The future of functional studies of marine mammal feeding is bright. Advances in new
technologies, as described earlier, will allow researchers to close the gap between experimental captive studies and field studies that are largely phenomological. As new fossils
Marine Mammal Physiology: Requisites for Ocean Living
other ursids, reflecting the increased biomechanical pressures for consuming a primarily
marine mammal diet (Slater et al. 2010). Polar bears tend to grasp their prey with their
mouths and break the neck or skull of their prey with their large masticatory muscles
and robust dentition. Interestingly, their cranial morphology and feeding biomechanics
demonstrates a potential trade-off leaving polar bears less effective at processing tough
food matter associated with omnivory (e.g., plants) (Slater et al. 2010). An ecomorphological study of craniodental morphology of all bears in relation to diet demonstrates significant morphological separation among bears that exhibit omnivory, herbivory, carnivory,
and insectivory. Only polar and brown bears exhibit significant carnivory. Craniodental
adaptations include a reduction in molar size, flexible mandibles, and relatively small carnassial blades. Polar bear feeding adaptations have more in common with omnivorous
canids. The less than robust feeding apparatus that might be expected from polar bears
can be explained by the fact that polar bears target ringed and bearded seal pups and
seals that are under 2 years of age (King 1983). These seals are much smaller in body size
and are much more vulnerable than larger prey. The size discrepancy suggests that polar
bears can overpower their prey without the need for craniodental adaptations (Sacco and
Van Valkenburgh 2004) that are typical in carnivorous canids that hunt large prey (Van
Valkenburgh and Koepfli 1993). However, polar bears are capable of taking larger prey
such as walruses and beluga whales (King 1983; Sacco and Van Valkenburgh 2004).
5.3 Tools and methods for studying feeding
strategies in marine mammals
Marine mammals are notoriously difficult to study both in the wild and in c aptivity.
As a consequence, much work on feeding mechanisms has been morphological.
Morphology can be used to predict function, but with caution, and should be considered
functional hypotheses until function can be verified by other methods. Regardless, craniodental morphology can be very instructive for investigating feeding mechanisms. Indeed,
new methods such as computed tomography, 3D reconstruction, 3D printing, finite element
analyses, physical and computation biomechanical modeling, materials science, and geometric morphometric are providing new and exciting frontiers in morphological research.
Advances in camera, video, computing, and electrophysiology capabilities and the reduction in size and increased portability are now allowing pool-side performance experiments that could have only been conducted in the laboratory in the past. This translates
into additional focused and experimental captive studies, which quantitatively measures
kinematics, performance, physiology, and behavior. Such experiments interface well with
field studies in which a cadre of animal-borne tags on free-ranging animals collects data
from foraging bouts and events in the open ocean. Such tools include integrated systems
that incorporate time–depth recorders with video systems, oceanographic data collection
systems, and 3D movement sensors (accelerometers, magnetometers, and gyroscopes) that
can record behavior, body movement, visual perspective, acoustics, and physiology. New
unmanned aerial vehicles (UAVs) are providing new access and perspective to animal
behavior and beyond. It is an exciting time to be a marine mammalogist.
5.4 Future directions
The future of functional studies of marine mammal feeding is bright. Advances in new
technologies, as described earlier, will allow researchers to close the gap between experimental captive studies and field studies that are largely phenomological. As new fossils